//
// Created by root on 2019/11/6.
//

#ifndef THREADLOCALSINGLETON_H
#define THREADLOCALSINGLETON_H
#include "../noncopyable.h"

#include <cassert>
#include <pthread.h>

namespace tank
{
    template<typename T>
    class ThreadLocalSingleton : noncopyable
    {
    public:
        ThreadLocalSingleton() = delete;
        ~ThreadLocalSingleton() = delete;

        static T& instance()
        {
            if (!t_value_)
            {
                t_value_ = new T();
                deleter_.set(t_value_);
            }
            return *t_value_;
        }

        static T* pointer()
        {
            return t_value_;
        }

    private:
        static void destructor(void* obj)
        {
            assert(obj == t_value_);
            typedef char T_must_be_complete_type[sizeof(T) == 0 ? -1 : 1];
            T_must_be_complete_type dummy; (void) dummy;
            delete t_value_;
            t_value_ = 0;
        }

        class Deleter
        {
        public:
            Deleter()
            {
                pthread_key_create(&pkey_, &ThreadLocalSingleton::destructor);
            }

            ~Deleter()
            {
                pthread_key_delete(pkey_);
            }

            void set(T* newObj)
            {
                assert(pthread_getspecific(pkey_) == NULL);
                pthread_setspecific(pkey_, newObj);
            }

            pthread_key_t pkey_;
        };

        static __thread T* t_value_;
        static Deleter deleter_;
    };

    template<typename T>
    __thread T* ThreadLocalSingleton<T>::t_value_ = 0;

    template<typename T>
    typename ThreadLocalSingleton<T>::Deleter ThreadLocalSingleton<T>::deleter_;

}  // namespace tank
#endif //THREADLOCALSINGLETON_H
